Please note that some countries did not have a separate Naval Aviation arm, i.e.
aircraft and flying units under control of the corresponding navy, so that the symbols
indicated under 'Naval Aviation' were, of course, in these cases, air force unit types.
The designations of flying units in the various air forces varied, as did the rank of
the comanders of the various echelons. Air arms owned or even influenced by the army
tended to have the same designations and ranks as ground units, possibly with the
prefix 'Flying ...' or 'Air ...'. Rank is not the final indication of the size of the
unit, or even the authorized rank of the commander. Take the Greek Air Force in
October 1940 for example, where company-sized flying units were commanded by Lieutenant
Colonels as well as Majors and Captains. On the other hand a low state of mobilization
might mean that many officers commanding were one or two ranks under the authorized
ones. For example, on 7 December 1941 not one USAAF Air Group (regiment-sized unit)
was commanded by a full Colonel. In other air forces, in some cases, Captains
commanded regiment or even brigade-sized units.
The number of aircraft in a unit varied. Company-sized flying units had 6 to 12
aircraft. Battalion-sized flying units 12 to 24 aircraft. Regiment-sized units had 20
plus. Units with small aircraft (one or two crew members) tended to have more
aircraft in them than those with large aircraft (which had more engines, a larger
aircraft crew, more numerous gound maintenance men, etc.). In addition, the difficulty
is also in determining whether the numbers indicated are 'on hand' as opposed to
'authorized' aircraft, or include 'reserve', 'sidelined', 'in maintenance', etc.